Method for marking of coagulation sites on a retina as well as a system for coagulating the retina

ABSTRACT

A method for marking coagulation sites on a retina by application of a light source including projecting a serial spot sequence from a sequential, one-dimensional series of spots on the retina, wherein the individual spots indicate the coagulation sites; waiting for confirmation of the sequence of individual spots; after confirming, recalculating an automated sequence of steps having a further serial spot sequence and projecting them on the retina according to the first step; and subsequent repeating of the second and third steps. Also, a system for coagulating the retina, having an imaging diagnostic unit, a therapy beam for coagulating coagulation sites, a pilot beam for marking the coagulation sites by a spot sequence, a beam deflecting unit for generating the spot sequence and for positioning the therapy beam, an electronic control unit for controlling the above devices, a software interface, and an interactive interface.

PRIORITY CLAIM

The present application is a divisional of U.S. application Ser. No.13/320,727 filed Nov. 15, 2011 entitled “Method for Marking ofCoagulation Sites on a Retina as well as a System for Coagulating theRetina” which is a National Phase entry of PCT Application No.PCT/EP2010/002968, filed May 14, 2010, which claims priority from GermanApplication No 102009021604.9, filed May 15, 2009, the disclosures ofwhich are hereby incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The invention relates to a method for marking of coagulation sites on aretina by means of a light source as well as a system for coagulatingthe retina for executing such a method.

BACKGROUND

The use of focused light from an axial high-pressure lamp for thetreatment of various diseases of the retina, e.g., diabetic retinopathy,by means of the light coagulation has been known for decades. Nowadays,the retina is warmed up or coagulated during light coagulation by meansof a laser beam, wherein the energy of the laser beam is absorbed by thedark coloring of the pigment epithelium within the retina. As a result,the metabolism is focused on the as yet healthy areas of the retina. Inaddition, biochemical cofactors are stimulated. This way, the progressof the disease is considerably slowed or stopped.

However, it is hereby disadvantageous that tissue worthy ofpreservation, particularly the photoreceptor layer located in beamdirection in front of the retinal pigment epithelium, is also destroyed.Therefore, solutions have been provided which minimize the destructionof tissue worthy of preservation, wherein the local treatment isterminated once a defined temperature is reached at the coagulationpoint. Hereby, a temperature-controlled coagulation system with acontinuous coagulation laser and a pulsed measuring laser as well as adetector, a control device, and an interrupter is used. Thereby, thecoagulation laser is designed is such a way that a coagulation beam isemitted and that the measuring laser generates a temperature-dependentmeasurement signal for the detector in the target area of thecoagulation laser. Thereby, the detector exhibits a temperature sensorthat detects a signal which allows for conclusions regarding thetemperature at the coagulation point. The signal detected by thedetector is transmitted to the control device which activates theinterrupter once a predetermined temperature is reached, therebyinterrupting the beam of the coagulation laser.

The coagulation points are periodically adjusted manually by theoperator who individually triggers the coagulation beam. This is verytime-consuming and the success of the treatment greatly depends on theabilities of the operator; therefore, it was suggested in WO 2007/035855A2, e.g., to provide a system and a method, wherein a pattern ofcoagulation points is provided from which the operator can choosebeforehand and/or combine the various patterns with one another.Thereby, two-dimensional arrangements of coagulation points areconsidered patterns which, for example, exhibit a matrix of 2×2, 3×3,4×4, 5×5, etc., wherein the distances of adjacent coagulation pointsremain constant. This prior art also provides other two-dimensionalpatterns, e.g., arrangements on a circle and/or on concentric circles,elliptical and sector-shaped arrangements.

However, such fixed patterns of regular geometry are disadvantageousbecause very often they do not correspond to the morphologicalconditions of the physiological anomalies. Therefore, recoagulation witha second or third coagulation pattern up to a single-burst coagulation,which was to be overcome with said method, is frequently required forefficiently executing a completely effective panretinalphotocoagulation. Even though it is possible with the above-mentionedprior art to achieve a large pattern which leads to an increase in thespeed of the treatment, the risk of overcoagulation and/orundercoagulation through the changeable focus remains due to the retinalcurvature and/or varying absorption behavior of the present ocularmedia.

SUMMARY OF THE INVENTION

Therefore, the problem addressed by the invention is that of allowingfor a laser treatment, for example retina coagulation, lasertrabeculoplasty, or an optimized panretinal photocoagulation, at veryhigh treatment speed, wherein only pathological areas but no healthyareas are coagulated. Thereto, the marking of coagulation sites, visibleto the operator before the treatment, by means of a method shall beensured, and a system for coagulation shall be provided which allows forthe execution of such marking.

This problem is solved through a method for marking of coagulationssites on a retina by means of a light source with the features discussedherein. Projecting a serial spot sequence of the light source from asequential, one-dimensional series of individual spots on the retina bymeans of a beam deflection unit, wherein the individual spots indicatethe coagulation sites. This indicates to the operator beforehand, i.e.,before the actual coagulation takes place, on which sites thecoagulation is to occur. Waiting for confirmation of the sequence ofindividual spots by means of entry of a confirmation signal ensures thatno coagulation sites are treated which are to be spared, e.g., becausethey contain healthy tissue. After confirming the sequence of theindividual spots, according to the invention, an automated sequence ofsteps having a further serial spot sequence and projection of the sameon the retina is recalculated. The use of a sequential, one-dimensionalseries of individual spots, which are created automatically, leads, whencompared to a manual determination of said individual spots, to asignificant increase in speed. Contrary to the provision of very complextwo-dimensional and large patterns, the method, according to theinvention, is advantageous because a confirmation must be entered by theoperator for every individual sequential, one-dimensional series inorder to subsequently—this not being subject matter of the methodaccording to the invention—execute the coagulation on said sites. As aresult, coagulation of healthy tissue is avoided and only thosecoagulation sites are accepted which are actually necessary for thehealing process. Through the repetition of the above-mentioned stepsaccording to the invention, it is possible to mark a large area of theretina with coagulation points in a short period of time.

In an advantageous development of the invention, the sequential,one-dimensional series of individual spots exhibits equidistantdistances and the progression of which is straight or curved as well ascontinuous or non-continuous. Due to the different indicatedpossibilities of placing the individual spots, the conditions in respectof the pathological areas of the retina as well as the present ocularmedia, such as astigmatism or other types of defective vision of the eyeto be treated can be taken into account.

A further advantageous development of the invention provides for thetemporal series of the spot sequence to have an interval between spotsaccording to one example 1 ns and 5 s, preferably between 1 μs and 1 s,particularly preferred between 40 ms and 0.5 s. The above-mentionedtemporal upper and lower limits are advantageous for an expeditiousexecution of the method while simultaneously ensuring good monitoring bythe operator.

In a further advantageous development of the invention, an automatedsequence of steps provides for an equidistant translation and/orrotation. As a result, multiple patterns can be produced which can bederived from a very simply arranged basic pattern, i.e., the sequential,one-dimensional series. Once again, it is possible to take into accountthe individual conditions of the retina to be treated.

Thereby, the sequential, one-dimensional basic pattern can be applied atany random site and completed through translation and/or rotation inrandom directions.

Hereby, the term “pattern” is used synonymously with the terms“sequence,” or “series.” The consecutively produced, manipulableindividual spots form a first basic sequence, from which an overallpattern is produced through translation and/or rotation.

A further advantageous development of the invention provides for thelight source to radiate laser light, particularly in the red range. Theuse of laser light in the red range has the advantage of producingindividual spots which are easily recognizable on the retina by theoperator.

A further advantageous development of the invention provides for anactive influence by the operator through variation of one or severallaser parameters prior to the confirmation of the next spot sequence.This results in an optimal adjustment of the required parameters in avery short period of time, wherein the operator does not have to waitfor the system to display the spot sequence required at this moment.

A further advantageous development of the invention provides for theconfirmation by means of a joystick, voice recognition, or a footswitch, particularly a multimodal foot switch. By means of theabove-mentioned device, a simple and precise input for confirming theseries of individual spots suggested by the system can be made by theoperator.

A further advantageous development of the invention provides for theconfirmation to take place only after the change of positions of therecalculated spot sequence. As a result, the individual conditions ofthe retina to be treated can be taken into account particularly wellbecause individual series of individual spots suggested by the systemcan be rejected, and therefore coagulation takes place only atrecalculated individual spots which meet the requirements for anintended coagulation but not at unintended sites.

A further advantageous development of the invention provides for thedistance between a next spot sequence and a previous spot sequence to bebetween zero and ten times that of the spot diameter, particularlypreferable between 0.8 and 1.5 times the spot diameter. This allows fora variation which extends from a superimposition of the spots, i.e., anenlargement of the spot surface, to a distance with sufficient spacebetween the individual spots. Therefore, a good individual treatment ofthe retina is possible.

A further advantageous development of the invention provides for achange of the distance of the starting position, orientation, length,inner-sequence distance, type of spot sequence, rotation, translationand/or step length of the spot sequence with reference to the previousspot sequence to be initiated by the operator and/or based on previouslydetermined examination data of the retina. Said very comprehensiveoption of changing the individual spots—their individual configurationas well as their spatial arrangement to one another—allows in turn forthe best possible treatment solely on the intended sites. Since theconcrete definition and determination of the above-mentionedcharacteristics of the spot sequence is possible due to the previouslyacquired examination data of the retina, a completely automatedcoagulation, adjusted to the retina treated moments ago, can beautomatically executed exclusively on the actual intended sites. Theterm inner-sequence distance indicates the distance between two adjacentindividual spots within the sequence. The inner-sequence distance is notkept constant but changes from one individual spot to the next.

A further advantageous development of the invention provides for atemperature determination of the individual spot during the use of atherapy beam. As a result, only a brief coagulation of the retinalpigment epithelium is realized without damaging the overlyingphotoreceptor layer. Thereby, the therapy beam is preferably deactivatedwhen a predetermined temperature is reached which is particularlyidentical for all individual spots.

A further advantageous development of the invention provides for theindividual spots to encircle the coagulation sites. This allows for theoperator to precisely determine what the treatment area, which is toundergo coagulation through the therapy beam, looks like and whether acoagulation is indeed to be executed over the entire area.

However, the herein described method for marking defined sites on aretina is not only applicable to a subsequent coagulation of the retinabut, for example, also for an iridectomy or iridotomy of the iris.

The problem is also solved through a system for coagulating the retinawith the features as disclosed herein.

In an example application, the system for coagulating the retina, havingan imaging diagnostic unit, a therapy beam for coagulating coagulationsites, a pilot beam for marking the coagulation sites by means of a spotsequence, a beam deflecting unit for generating the spot sequence andfor positioning the therapy beam, an electronic control unit forcontrolling the above devices, a software interface, and an interactiveinterface, is used for executing the method described above.

By means of the imaging diagnostic unit, the operator can determineprior to executing the coagulation, at which concrete site of the retinasaid coagulation should be performed since the spot sequences marked bythe pilot beam can now be observed. The therapy beam is used forcoagulating the coagulation sites which were marked with the pilot beambeforehand. Therapy beam and pilot beam are controlled by a beamdeflecting unit in such a way that the spot sequences of the pilot beamare projected onto the retina and that the therapy beam performs thecoagulation on the marked individual spots after clearance through theconfirmation by means of the confirmation signal. The entire process iscontrolled by the control unit which particularly controls theactivation of the therapy beam as well as the beam deflection within thebeam deflecting unit. The entire process is executed via a softwareinterface. By means of the interactive interface, the confirmation bymeans of the confirmation signal is effected which is necessary foractivating the therapy beam once the marking of the individual spots ofthe coagulation sites were indicated to the operator by means of thepilot beam.

In an example embodiment, the imaging diagnostic unit is a laser slitlamp, a fundus camera, or a scanning laser ophthalmoscope.

A number of light sources, such as LEDs, superluminescent diodes, gasdischarge lamps, and particularly lasers are suited as therapy beam.Thereby, a multiwavelength laser, which can emit different colors in thevisible range, is preferably used. Particularly preferable are thecolors green, yellow, and red. Furthermore, it is also preferable forthe multiwavelength laser to emit light in the near infrared range. Thedifferent indicated wavelengths make it possible to reach differentcoagulation depths. Due to the photopigment melanin, the highestabsorption takes place in the green wavelength range (from 514-550 nm);the highest absorption of the blood pigment hemoglobin is achieved inthe yellow spectral range (550-580 nm); however, coagulation at a hightissue penetration takes place because of the red wavelengths (630-690nm) or by application wavelength in the near infrared range (e.g., at810 nm).

For coagulating the retina, pulse durations between 10 ms and 100 ms,particularly between 20 ms and 50 ms, have proven successful for thetherapy beam.

Even though pulse durations below 20 ms ensure an almost painlesstreatment, the effect of the treatment must be expected to be inferior.By contrast, a superior treatment effect must be expected with pulsedurations above 50 ms but which can lead to scarring of the treatedsites.

A high coagulation effect, wherein resulting scarring diminishes overtime, is achieved with pulse durations between 20 ms and 50 ms.Therefore, pulse durations between 20 ms and 50 ms are recommended forthe solution for coagulating the retina as described herein.

A further advantageous development of the invention provides for thepilot beam to be a laser diode which preferably radiates in the redrange. The resulting markings on the retina—as already describedabove—are easily identifiable by the operator.

A further advantageous development of the invention provides for thebeam deflecting unit to coaxially project the pilot beam and the therapybeam onto the retina. This ensures that the coagulation by applicationof the therapy beam takes place exactly at the position indicatedbeforehand by the pilot beam to the operator who cleared said positionby means of a confirmation signal. This ensures that the retina is notcoagulated in sites which should not be coagulated, for example, becausethey still contain unimpaired tissue.

A further advantageous development of the invention provides for thebeam deflecting unit to exhibit movable lenses, mirrors, or diffractivebeam splitters in the beam path. In prior art, these are well-known,reliable devices for beam deflection. Said lenses or mirrors arepreferably controlled via motors; this particularly refers togalvanometrically controlled mirrors, piezo scanners, or micromirrorarrays.

A further advantageous development of the invention provides for thecontrol unit to be a microcontroller which exhibits at least one inputinterface and one output interface and which is programmable. Thisallows for previously determined values about the retina to be treatedas well as the present ocular media to be entered into the control unit,which therefore knows the individually required data for the pendingtreatment and can adjust the respective series of individual spots tothe present concrete conditions. As a result, it will periodically notbe necessary for the operator to refuse clearance of the displayedseries of individual spots and for the system to calculate and displayto the operator an alternative series. Instead, every one of thedisplayed series can be cleared by the operator, leading to anaccelerated treatment as well as increased reliability of the treatment.

A further advantageous development of the invention provides also for aninterrupter which prevents at least one specific wavelength range of thetherapy beam from impinging on the coagulation site. As alreadydescribed above, the penetration of the radiation of the therapy beam,and therefore the coagulation, can be controlled through the use ofdifferent wavelengths. Therefore, the interrupter specifies differentpenetration depths of the therapy beam at a predetermined individualspot or for an entire series of individual spots. Preferably, saidinterrupter is a filter which can be introduced into the therapy beam.

A further advantageous development of the invention provides for theinterrupter to be a device which deactivates the therapy beam,particularly in the form of an aperture in the area through which thetherapy beam passes. As a result, the coagulation can be altogethercompleted and not only selectively in one or different depths as is thecase with the previously described filter.

A further advantageous development of the invention additionallyprovides for a device for temperature determination for determining thetemperature at the coagulation site while the therapy beam is directedat said site. As already described above, the photoreceptor layer abovethe pigment epithelium to be treated can thereby be excluded fromdamage. Temperature determination is preferably effected by means of adetector within the device for temperature determination, which recordspressure waves from the coagulation site. Since the device fortemperature determination is connected to the interrupter, the therapybeam can immediately be deactivated once the predetermined temperatureis reached, resulting in the above-mentioned effect, i.e., thephotoreceptor layer will not be damaged. Hereby, an indirect connectionof the device for temperature determination via the control unit can beprovided in addition to the direct connection to the interrupter.

A further advantageous development of the invention provides for thesystem to be prepared for irradiating every individual spot of theserial spot sequence through the therapy beam with an individual size,form, wavelength, and duration. This also serves the individualtreatment of every site of the retina. By adjustment of the parametersof size and form, the treatment area at the respective coagulation sitecan be precisely adjusted to desired size and form. By wavelengthadjustment, a specific depth of coagulation can be achieved within theretina, as already described above. As a result, a depth-modulated lasercoagulation is possible for all coagulation sites. Through adjusting theduration, the temperature of the individual coagulation sites can bevaried, resulting in the degree of coagulation of the retina. Therefore,a coagulation degree-modulated laser coagulation is possible for allcoagulation sites. The size of the individual spots can be varied to alarge extent; preferably the diameters are in a range between 50-1000μm. Thereby, the size of the individual spots can be modulated within aseries of individual spots (which can be designed particularly as astraight line) or through a change of the sizes of the individual spotsfrom line to line.

In addition to a preferably homogenous laser therapy of the retina witha predetermined equidistant grid, a predetermined equal temperature, anda predetermined equal treatment depth due to the applied wavelength, amultidimensional modulation of the degree of treatment of the retina isalso possible with a system, according to the invention, which exhibitsa monochromatic laser or a polychromatic laser system, an ophthalmicscan system, and a temperature measuring system. For example, this canresult in the same therapeutic benefit for the patient without having tocompletely coagulate excessively large areas of the retina and to losesaid areas for the ability to see. Simultaneously, however, a retinaldetachment and therefore aggravated progress of the disease is avoided.

For example, this is possible because classic coagulation spots are setin a rough grid and sub-coagulative treatment occurs in the intermediatespaces without damage to the photoreceptors. Thereby, this method ispossible line by line or within a pattern.

A selective retina therapy can also be performed on the basis of aμ-second laser pulses. Thereby, the selective absorption of theparticularly green laser light is utilized within the retinal pigmentepithelium and ensures by means of the temporally limited exposure inthe μ-second range that, within the thermal relaxation time, almost theentire heat remains in the selectively absorbing pigment epithelium anddoes not reach the photoreceptor layer. This induces the damaged pigmentepithelium to regenerate without showing any visible damage in thefundus image.

A different selective retinal therapy is executed in planar fashion byapplication of a scanned CW laser beam. Thereby, the exposure time isappropriately limited through the scanning speed within the thermalrelaxation time.

With a controlled, selective retina coagulation, different absorptionproperties in the retinal pigment epithelium and different localtransmissions of the ocular media are taken into account. As a result,locally different zones of damage of the retinal pigment epithelium canbe treated.

An optoacoustic measuring system or an optical measuring system, forexample, are used as temperature measuring system. By choosing awavelength in the yellow, green, red, or infrared spectral range, ahomogenous coagulation depth or hyperthermia depth can be set. Choosingequidistant individual spot distances and their diameters allows for astructuring of the homogeneity within the surface.

A targeted planning of the treatment for the best possible individualtherapy is possible due to diagnostic data ascertained beforehand. Suchdata were ascertained particularly on the basis of fundus images (colorimages, angiography images, autofluorescence images, etc.), OCT images(optical coherence tomography), or confocally scanned images.Subsequently, the treatment is performed by a partly or fully automatedgeneration of treatment parameters and a partly or fully automatedexecution of the treatment.

The following lasers are used: E.g., argon lasers, diode lasers,diode-pumped solid-state lasers, diode-pumped semiconductor lasers,fiber lasers, and frequency-doubled Nd:YAG lasers. The lasers can beapplied as pulsed laser or CW laser.

The programmed control unit is preferably designed as hard-wiredprogrammed or stored-program controller. Preferably, the controllerexhibits a processor architecture.

The positioning of the focused laser beam is effected automatically orsemiautomatically by use of deflection elements which can deflect thebeam two-dimensionally. For example, this can be effected throughgalvanometric mirror scanners, piezo-driven optical elements,acousto-optical elements, electro-optical elements, or laterally movinglenses. Thereby, the beam positioning elements can move the beam in atranslative, torsional, tilted, or rotating fashion. Said elements canbe reflecting as well as refractive in transmission.

The therapy beam is either parallel or bundled. For example, it exhibitsan elliptic, preferably circular polarization. However, it is alsopossible to use linearly polarized or unpolarized therapy beams.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details of the invention are described as follows by means ofthe attached figures:

FIG. 1 shows a series of patterns of individual spots originating fromone another through translation;

FIG. 2 shows a series of patterns of individual spots originating fromone another through rotation;

FIG. 3 shows a series of patterns of individual spots originatingthrough translation and change of the initial position as well asomission of a spot sequence;

FIG. 4 shows two patterns of individual spots originating throughtranslation and change of the length of the sequence;

FIG. 5 shows a pattern of individual spots originating throughtranslation, change of the starting point and length of the sequence;

FIG. 6 shows a pattern of individual spots originating throughtranslation and change of the distances between the individual spots;

FIG. 7 shows patterns of individual spots originating through rotationof individual spots arranged on a circular arc;

FIG. 8 shows patterns of individual spots originating through rotationof individual spots arranged as circle segment;

FIG. 9 shows a pattern of coagulation sites originating through lateralchange, change of size, change of the length of the sequence and theinner sequence distance;

FIG. 10 shows a series of coagulation sites which are coagulated withdifferent wavelengths;

FIG. 11 shows a series of coagulation sites which are coagulated throughdifferent temperatures; and

FIG. 12 depicts a system for coagulating the retina according to anexample embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 shows in the first depiction from the left the basic form of asequential, one-dimensional series of individual spots, which serves asstarting point for the additional depictions of FIG. 1 and theirmultiple applications, as described in the following.

The series consists of eight individual spots which are arrangedequidistantly to one another and run in vertical direction. The firstindividual spot is the depicted individual spot in the top position.Starting with said spot, the sequence is generated continuously from topto bottom in the depicted order.

Starting from said basic form, a pattern of individual spots—depicted inthe second drawing from the left—arranged equidistantly to one anotherin a 7×16 matrix is obtained through a translation of the basic verticalseries in the left drawing.

Deviating from the basic form depicted in the first drawing from theleft, the sequential, one-dimensional series can also exhibit ahorizontal or other direction. Starting with the respective basic form,the patterns depicted in the additional drawings in FIG. 1 can beobtained. Thereby, the size of the matrix of individual spots arrangedequidistantly to one another depends on the number of translations.

The left drawing of FIG. 2 shows a shortened initial sequence with fourindividual spots when compared to the basic sequence in FIG. 1 witheight individual spots. The pattern in the second depiction from theleft is obtained from the basic sequence in the left depiction in such away that advancing from left to right one rotation each is achievedaround a rotation center (not depicted) with an alternating sequencelength between three and four individual spots, wherein the sequenceswith three individual spots are set in the gaps of the sequences withfour individual spots. This is achieved in such a way that, in additionto the rotation, a translation of the initial individual spots isadditionally executed in transverse direction.

By contrast, the second drawing from the right in FIG. 2 shows a plainrotation between the first series of individual spots running invertical direction and the second series slightly rotatedcounterclockwise as a result. The initial series as in FIG. 1 alsoexhibits eight individual spots, but the distance between the fourth andfifth individual spot is significantly greater. Said distance is chosenin such a way that no individual spots are present in a depicted circle.The rotation center is also the center of the depicted circle. Acontinuous and repeated rotation around the same angle of rotationindicated in the second drawing from the right in FIG. 2 results in theradial drawing on the right in FIG. 2.

An irregular translation (which can also be called a modification of theinitial position) is executed in the two left drawings in FIG. 3.Thereby, a vertical initial series of five individual spots is shown inthe left drawing.

The second drawing from the left shows a vertical initial series of sixindividual spots which similar to the two drawings on the right of FIG.2 exhibits an increased distance between the upper half and the lowerhalf (inner sequence distance) of the respective three individual spots.

However, in the third drawing from the left in FIG. 3, a vertical seriesof seven individual spots is completed to a pattern through a consistenttranslation; however, said pattern is altered in respect of the form ofthe individual spots between the first and second (as well as the fifthand sixth) series relative to the third and fourth (as well as theseventh) series in such a way that the latter spot positions can beomitted by the operator, i.e., they do not constitute coagulation sites.

The right drawing in FIG. 3 shows a special application, wherein thegrey line represents a blood vessel. The operator omits those spotpositions which would impinge on the blood vessel.

In the two drawings on the left in FIG. 4, translations and changes inthe sequence length with vertical symmetry of the spot sequence aresuperimposed. In the right drawing this leads to a pattern whichrepresents a triangle with decreasing sequence length from left toright.

In the drawing on the right in FIG. 4, a translation is alsosuperimposed with a change of the sequence length of the spot sequencebut the sequence length varies due to the absence of symmetry.

FIG. 5 shows an irregular pattern which is obtained through the initialseries of four vertical individual spots, as depicted on the very left,through varying the sequence length, translation, and change of theinitial positions.

FIG. 6 shows a pattern which is formed through translation of a basicform in vertical direction. Contrary to the previous patterns, thedistances of the individual spots of the basic form are changed withevery translation, resulting in a pattern in the form of a “fanned out”6×6 matrix.

The patterns in FIG. 7 and FIG. 8 are, in contrast to the previouslydescribed patterns, not based on the basic form of a sequential,one-dimensional series of individual spots in accordance with thedrawing on the left in FIG. 1. Similar to the two drawings on the rightin FIG. 2, no individual spots are present within the depicted circle.

The drawing on the left in FIG. 7 shows the applied basic form as acircular arc of individual spots. Through a slight rotation, this basicform in the form of a circular arc results in the pattern depicted inthe second drawing from the left, and a 180° rotation results in thepattern depicted in the third drawing from the left. Through multiplerotations in conjunction with the omission of spot positions by theoperator, said basic form can be completed to a pattern in the form of afull circle.

According to the drawing on the left in FIG. 8, a circular segment,wherein individual spots are arranged, is used as basic form in thisembodiment. Starting with said basic form in the form of a circularsegment, the pattern depicted in the second drawing from the left can beproduced with a single rotation, and the third drawing from the left canbe produced through multiple rotations. As can be seen in the drawing onthe right in FIG. 8, the patterns can be reduced once again by theoperator through omission of spot positions. Preferably, the inner arcforms the basic sequence in the circular segment. In order to “fill” thecircular segment, the following sequence is produced on a greaterradius, wherein, as a rule, the distance and the number of individualspots in the basic sequence are enlarged. This approach is advantageousbecause the innermost arc, i.e., the basic sequence, is placed near themacula where the demands are highest. Said demands decrease accordinglyin the outward direction.

The patterns shown in FIGS. 1 to 8 are only exemplary and can bemodified arbitrarily for producing any desired pattern. This allows fora precise response to the individual case to be treated and for settingthe patterns in such a way that coagulation occurs solely at therequired coagulation points. The individual spots shown in FIGS. 1 to 8are produced by the pilot beam, and the therapy beam will subsequentlycoagulate said sites.

Based on a series of individual spots in horizontal direction, FIG. 9shows a pattern, wherein the uppermost row was altered throughmodification of the sequence length as wells as the inner sequencedistances. However, these are not the points marked by the pilot beambut the coagulation sites subsequently caused by the therapy beam.Hereby, the coagulation sites are varied according to the respectivesize of the coagulation site required for the individual case.Preferably, the diameters of such coagulation sites range from 50 to 500μm.

In addition to a translation in vertical direction, a change of thediameter of the individual spots was also made between the lowest andsecond to lowest (and also between the second to lowest and second tohighest) series of individual spots. However, between the second seriesfrom the top and the uppermost series, not only a partial change of thediameter of the individual spots was made (i.e., every other individualspot was reduced from the size in the second series from the top to asize according to the second series from the bottom) but also a sequenceextension from four to seven individual spots as well as a change in theinner sequence distances was executed.

FIG. 10 shows a grid of coagulation points with equal diameters whichwere irradiated with different wavelengths. Hereby, a wavelength of 577nm was used for yellow light (550-580 nm), a wavelength of 532 nm forgreen light (514-550 nm), and a wavelength of 659 nm for red light(630-680 nm). The series from left to right is as follows: Yellow,green, red, green, yellow, green, red. Due to the different appliedwavelengths, the primary absorption of energy in the retina takes placein different depths. As a result, coagulation occurs in the upper areaof the retina due to the highest absorption of the blood pigmenthemoglobin in the yellow spectral range. The highest absorption in thegreen wavelength range is caused by the photopigment melanin, resultingin coagulation in the medium depth of the retina. Red wavelengths causethe deepest penetration in the retina, resulting in the highest degreeof coagulation.

Due to the targeted irradiation of different coagulation sites withdifferent wavelengths (colors), a depth modulation can be achieved. As aresult, the individually required treatment can be taken into account.

FIG. 11 shows the same row of coagulation sites as FIG. 10. However, inFIG. 11, a modulation with different coagulation temperatures instead ofdifferent light wavelengths is executed. Hereby, coagulation occursmonochromatic at a wavelength of, e.g., 532 nm (i.e., in the greenwavelength range). Due to the different coagulation temperatures of,e.g., 45°, 50°, 60°, different degrees of coagulation are achievedwithin the depicted coagulation sites. Thereby, the length of the arrowsindicates the degree of coagulation in the retina, wherein long arrowsrepresent a higher degree of coagulation than shorter arrows. Thisresults in an equidistant, monochromatic coagulation degree-modulatedlaser coagulation or hyperthermia.

Referring to FIG. 12, in an example embodiment, the system forcoagulating the retina, having an imaging diagnostic unit 1, a therapybeam source 4 emitting a therapy beam for coagulating coagulation sites,a pilot beam source 5 emitting a pilot beam for marking the coagulationsites by means of a spot sequence, a beam deflecting unit 2 forgenerating the spot sequence and for positioning the therapy beam, anelectronic control unit 8 for controlling the above devices, a softwareinterface 9, and an interactive interface 10, is used for executing themethod described above.

By application of the imaging diagnostic unit, the operator candetermine prior to executing the coagulation, at which concrete site ofthe retina said coagulation should be performed since the spot sequencesmarked by the pilot beam can now be observed. The therapy beam is usedfor coagulating the coagulation sites which were marked with the pilotbeam beforehand. Therapy beam and pilot beam are controlled by beamdeflecting unit 2 in such a way that the spot sequences of the pilotbeam are projected onto the retina and that the therapy beam performsthe coagulation on the marked individual spots after clearance throughthe confirmation by reception of the confirmation signal. The entireprocess is controlled by the control unit 8 which particularly controlsthe activation of the therapy beam source 4 as well as the beamdeflection within the beam deflecting unit 2. The entire process isexecuted via a software interface 9. By use of the interactive interface10, the confirmation by means of the confirmation signal is effectedwhich is necessary for activating the therapy beam source 4 once themarking of the individual spots of the coagulation sites were indicatedto the operator by use of the pilot beam.

For example, the imaging diagnostic unit 1 is a laser slit lamp, afundus camera, or a scanning laser ophthalmoscope.

A number of therapy beam sources 4 light sources, such as LEDs,superluminescent diodes, gas discharge lamps, and particularly lasersare suited to emit the therapy beam. Thereby, a multiwavelength laser,which can emit different colors in the visible range, is used, forexample. Particularly examples are the colors green, yellow, and red.Furthermore, it is also possible for the multiwavelength laser to emitlight in the near infrared range. The different indicated wavelengthsmake it possible to reach different coagulation depths. Due to thephotopigment melanin, the highest absorption takes place in the greenwavelength range (from 514-550 nm); the highest absorption of the bloodpigment hemoglobin is achieved in the yellow spectral range (550-580nm); however, coagulation at a high tissue penetration takes placebecause of the red wavelengths (630-690 nm) or by means of a wavelengthin the near infrared range (e.g., at 810 nm).

For coagulating the retina, pulse durations between 10 ms and 100 ms,particularly between 20 ms and 50 ms, have proven successful for thetherapy beam.

Even though pulse durations below 20 ms ensure an almost painlesstreatment, the effect of the treatment must be expected to be inferior.By contrast, a superior treatment effect must be expected with pulsedurations above 50 ms but which can lead to scarring of the treatedsites.

A high coagulation effect, wherein resulting scarring diminishes overtime, is achieved with pulse durations between 20 ms and 50 ms.Therefore, pulse durations between 20 ms and 50 ms are recommended forthe solution of coagulating the retina as described herein.

A further embodiment of the invention provides for the pilot beam to bea laser diode which for example radiates in the red range. The resultingmarkings on the retina as already described above are easilyidentifiable by the operator.

A further embodiment of the invention provides for the beam deflectingunit 2 to coaxially project the pilot beam and the therapy beam onto theretina. This ensures that the coagulation by means of the therapy beamtakes place exactly at the position indicated beforehand by the pilotbeam to the operator who cleared said position by entering of aconfirmation signal. This ensures that the retina is not coagulated insites which should not be coagulated, for example, because they stillcontain unimpaired tissue.

A further embodiment of the invention provides for the beam deflectingunit 2 to exhibit movable lenses, mirrors, or diffractive beam splittersin the beam path. In prior art, these are well-known, reliable devicesfor beam deflection. Said lenses or mirrors are preferably controlledvia motors; this particularly refers to galvanometrically controlledmirrors, piezo scanners, or micromirror arrays.

A further advantageous development of the invention provides for thecontrol unit 8 to be a microcontroller which exhibits at least one inputinterface and one output interface and which is programmable. Thisallows for previously determined values about the retina to be treatedas well as the present ocular media to be entered into the control unit,which therefore knows the individually required data for the pendingtreatment and can adjust the respective series of individual spots tothe present concrete conditions. As a result, it will not be necessaryfor the operator to periodically refuse clearance of the displayedseries of individual spots and for the system to calculate and displayto the operator an alternative series. Instead, every one of thedisplayed series can be cleared by the operator, leading to anaccelerated treatment as well as increased reliability of the treatment.

A further advantageous development of the invention provides also for aninterrupter 3 which prevents at least one specific wavelength range ofthe therapy beam from impinging on the coagulation site. As alreadydescribed above, the penetration of the radiation of the therapy beam,and therefore the coagulation, can be controlled through the use ofdifferent wavelengths. Therefore, the interrupter 3 specifies differentpenetration depths of the therapy beam at a predetermined individualspot or for an entire series of individual spots. In one example, saidinterrupter 3 is a filter which can be introduced into the therapy beam.

A further advantageous development of the invention provides for theinterrupter 3 to be a device which deactivates the therapy beam,particularly in the form of an aperture in the area through which thetherapy beam passes. As a result, the coagulation can be altogethercompleted and not only selectively in one or different depths as is thecase with the previously described filter.

A further advantageous development of the invention additionallyprovides for a device for temperature determination 6 for determiningthe temperature at the coagulation site while the therapy beam isdirected at said site. As already described above, the photoreceptorlayer above the pigment epithelium to be treated can thereby be excludedfrom damage. Temperature determination is preferably effected by meansof a detector 6 within the device for temperature determination, whichrecords pressure waves from the coagulation site. Since the device fortemperature determination is connected to the interrupter 3, the therapybeam can immediately be deactivated once the predetermined temperatureis reached, resulting in the above-mentioned effect, i.e., thephotoreceptor layer will not be damaged. Hereby, an indirect connectionof the device for temperature determination 6 via the control unit canbe provided in addition to the direct connection to the interrupter 3.

A further advantageous development of the invention provides for thesystem to be prepared for irradiating every individual spot of theserial spot sequence through the therapy beam with an individual size,form, wavelength, and duration. This also serves the individualtreatment of every site of the retina. By means of size and form, thetreatment area at the respective site can be precisely adjusted to thedesired size and form. By the wavelength adjustment, a specific depth ofcoagulation can be achieved within the retina, as already describedabove. As a result, a depth-modulated laser coagulation is possible forall coagulation sites. Through adjusting the duration, the temperatureof the individual coagulation sites can be varied, resulting in thedegree of coagulation of the retina. Therefore, a coagulationdegree-modulated laser coagulation is possible for all coagulationsites. The size of the individual spots can be varied to a large extent;preferably the diameters are in a range between 50-1000 μm. Thereby, thesize of the individual spots can be modulated within a series ofindividual spots (which can be designed particularly as a straight line)or through a change of the sizes of the individual spots from line toline.

1. (canceled)
 2. A system for coagulating the retina; comprising: animaging diagnostic unit; a therapy beam source generating a therapy beamthat coagulates coagulation sites; a pilot beam source generating apilot beam that marks the coagulation sites by a spot sequence; a beamdeflecting unit that generates a spot sequence and that positions thetherapy beam; a device for temperature determination that determines atemperature at the coagulation sites; an electronic control unit that isoperably coupled to and controls the imaging diagnostic unit, thetherapy beam source, the pilot beam source and the beam deflecting unit;and a software interface operably coupled to the electronic controlunit; and an interactive interface operably coupled to the electroniccontrol unit.
 3. The system according to claim 2, wherein the imagingdiagnostic unit comprises a laser slit lamp, a fundus camera, or ascanning laser ophthalmoscope.
 4. The system according to claim 2,wherein the therapy beam source comprises a light source selected fromthe following light sources: LEDs, superluminescent diodes, gasdischarge lamps and lasers.
 5. The system, according to claim 4, whereinthe therapy beam source generating a therapy beam that coagulatescoagulation sites generates therapy beam pulse durations between 10 msand 100 ms.
 6. The system, according to claim 4, wherein the therapybeam source that coagulates coagulation sites generates therapy beampulses by application of a micro-second laser.
 7. The system, accordingto claim 4, wherein the therapy beam source comprises a multiwavelengthlaser producing laser energy in the visible range, in at least one ofcolors green, yellow, and red or in a near infrared.
 8. The system,according to claim 4, wherein the therapy beam source that coagulatescoagulation sites generates coagulation spots line by line or within apattern.
 9. The system, according to claim 2, wherein the therapy beamsource generating the therapy beam includes a microsecond laser thatemits micro-second laser pulses that coagulate the coagulation sites andwherein the beam deflecting unit generates the spot sequence andpositions the therapy beam generates the spot sequence and positions thetherapy beam line by line or within a pattern.
 10. The system, accordingto claim 2, wherein the pilot beam source comprises a laser diode, whichradiates in the red range.
 11. The system, according to claim 2, whereinthe beam deflecting unit coaxially projects the pilot beam and thetherapy beam onto the retina.
 12. The system, according to claim 2,wherein the beam deflecting unit comprises movable lenses, mirrors, ordiffractive beam splitters in the beam path.
 13. The system, accordingto claim 12, wherein the beam deflecting unit comprises lenses ormirrors that are controlled via motors; and wherein the motors comprisegalvanometrically controlled mirrors, piezo scanners, or micromirrorarrays.
 14. The system, according to claim 2, further comprising aninterrupter that, when activated, prevents at least one specificwavelength range of the therapy beam from impinging on the coagulationsite.
 15. The system, according to claim 14, wherein the interruptercomprises a device that deactivates the therapy beam.
 16. The system,according to claim 15, wherein the interrupter comprises an aperture inan area through which the therapy beam passes.
 17. The system, accordingto claim 2, further wherein the device for temperature determinationdetermines the temperature at a selected coagulation site while thetherapy beam is directed at said selected coagulation site.
 18. Thesystem, according to claim 2, wherein the device for temperaturedetermination that determines the temperature at the coagulation sitedetermines the temperature while the therapy beam is directed at aselected coagulation site and further comprising a beam deflecting unitthat generates the spot sequence and that positions the therapy beamline by line or within a pattern.
 19. The system, according to claim 17,wherein the device for temperature determination comprises a detectorthat records pressure waves from the coagulation site.
 20. The system,according to claim 17, wherein the device for temperature determinationis connected to the interrupter indirectly via the control unit.
 21. Thesystem, according to claim 2, wherein the therapy beam is emitted by alaser that emits micro-second laser pulses that coagulate thecoagulation sites; and wherein the device for temperature determinationcomprises a detector that records pressure waves from the coagulationsite and is connected to the interrupter indirectly via the control unitand further wherein the beam deflecting unit that generates the spotsequence and that positions the therapy beam generates the spot sequenceand positions the therapy beam line by line or within a pattern.
 22. Thesystem, according to claim 2, wherein the system is adapted to irradiateevery individual spot of the spot sequence by application of the therapybeam with an individual size, form, wavelength, and duration.